Method of and means for controlling resistances



Aug. 17 1926. 1,596,704

c. w. YERGER METHOD 0F AND MEANS FOR CONTROLLING'RESISTANCBS Filed Feb. 28, 1919 INVENTOR. wins/W 1 'BY/IQ My ATTORNEY Patented Aug. 17, 1926.

UNITED STATES PATENT OFFICE.

CHARLES W. YERGER, OF WASHINGTON, DISTRICT COIJUMBIA, LAfiSIGNOR TO THE CUTLER-HAMMER MG. 00., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WIS- CONSIN.

METHOD OF AND MEANS FOR CONEI MLLING RESLSTANCES.

Application filed February 28, 1919. Serial No. 279,670.

This invention relates to a method of and means for controlling resistances for electric circuits, and particularly motor circuits.

An object of the inventionis to provide a method of resistance control whereby a given resistance divided into a given number of sections may be utilized to afford an increased number of resistance gradations of the circuit including the same and whereby the number of switches heretofore required for effecting such number of resistance gradations may be materially reduced. p

Another object of the invention is to provide a controller for carrying out the aforesaid method wherein the number of resistance controlling switches is reduced to a minimum.

Various other objects and advantages of the invention will hereinafter appear.

According to the invention it is proposed to employ resistance sections of appropriate ohmic value and capacity for series-parallel commutation, utilizing said sections in series, then excluding certain of said sections from circuit While retaining other of the same in circuit and then reincluding an excluded section or sections in parallel with the section retained incircuit, or vice versa.

The accompanying drawing exemplifies the proposed method and shows certain of the various forms of controllers which may be employed in the ,practice'of such method.

In the drawing Figure 1 is a schematic and diagrammatic View of a manual controller particularly adapted for motor control; and,

I Fig. .2 is a diagrammatic view of an electromagnetic controller. particularly adapted for motor control.'

Referring to Fig. 1, the resistance to be controlled, which comprises sections R, R and R is utilized as the starting resistance for an electric motor M, said resistance being controllable by a series of switch 1 to 4 inclusive respectively operable by cams 5 to 8 inclusive fixed to a shaft 9 having an operating handle 10.

The method of control exemplified in Fig.

1 consists in completing the motor circuit through the resistance sections R, R and R inseries, then progressively short circuiting resistancesections R and R thereafter progressively connecting resistance sections R and R in parallel with resistance section R and finally short-circuiting all of said resistances. Thus by this method three sections of resistance are utilized to atford six resistance gradations Whereas said resistance sections it utilized exclusively in either series or parallel relation, would atford only four gradations.

The contour of the respective cams and their arrangement upon the shaft 9 is such that upon movement of lever 10 in a clockwise direction'the respective switches will be closed in their numerical order, whereas upon closure of switch 3 switches 1 and 2 are released and following closure of switch 4, said switches 1 and 2 are again-closed progressively.

Closure of switchl completes circuit from line L by conductor 11 through said switch, by conductor .12 through resistances R, R and R in series, thence through the motor to line :L. Closure of switch 2 completes the circuit from conductor 11 through said switch, by conductor 13 to resistance R and thence as formerlyltraced. Closure of switch 3 completes circuit from conductor 11 through said switch, by conductor 14 to resistance R and thence as formerly traced. Upon closure of switch 4, switch 3 being closed and switches 1 and 2 being open, the circuit through resistance R as last traced is not interrupted but an additional circuit is established from conductor 14 through re sistance R by conductor 13 through switch 4, thence by conductor 15 through the motor to line L. Reclosure-of switch 1 establishes an additional circuit from conductor 11 through said switch, by conductor 12 through resistance R,-thence by conductor 13, as last traced. Reclosure of switch 2 completes circuit from conductor 11 through said switch, thence by conductor 13, switch 4 and -conductorl5 through the motor to line L. I

Thus the aforedescribed controller by means of three resistance sections and four control switches provides for starting and acceleration of the controlled motor in six distinct steps and also provides for deceleration and stopping thereof in a like number of steps, since obviously reverse ac tuation of lever 10 effects operation of the control switches in inverse sequence, thereby effecting the aforedescribed commutations in inverse order. It is therefore apparent that by the construction and arrangement described is effected a decided reduction in the number of resistance sections and control switches and hence in the size, weight and cost of a controller required to provide a desired number of control steps.

The controller illustrated in Fig. 2 similarly includes three sections RQRZR' of resistance utilized as the starting resistance for a motor M and controllable by a series of electro-responsive switches 21 to 24C inclusive, response of said switches being subject to delay by series relays 25 to 28 1nclusive respectively. Co-ordination of the electro-responsive switches is effected by means of auxiliary contacts thereof, the automatic action of the controller being re spectively initiated and terminated by means of a starting push button 29 and a stop button 30.

The electro-responsive switches are adapted to operate in the same cycle as that effected during motor acceleration by the corresponding switches of Fig. 1, aforedescribcd, and to effectprecisely similar commutation of the resistance sections.

Thus closure of switch 21 completes circuit from line L through the motor and field, thence by conductor 31 through the winding of relay 25, by conductor 32 through switch 21, thence through resistance R, by conductor 33 through resistance R", by conductor 34: through the winding of relay 27 thence through resistance R and by conductor 35 to line L. Closure of switch 22 completes the circuit to conductor 32 as formerly traced thence by conductors 36 and 37 through switch 22 and through the winding of relay 26 thence by conductors 38 and through resistance R and thence to line L as last traced. Closure of switch 23 completes circuit to conductor 36 as formerly traced, thence through the winding of relay 28 and through switch 23, thence through the winding of relay 27, through resistance R and thence to line L. Switches 21 and 22 being open and switch 23 being closed, closure of switch 24; completes a circuit through switch 23 as formerly traced, thence by conductor 34; through resistance R in the reverse direction, by conductors 33 and 39 through switch 2atthence by conductor 35 to line L, thereby connecting resistance R in parallel with resistance R Reclosure of switch 21 at this time serves to complete a further parallel circuit extending to conductor 32 as formerly traced, thence through switch 21 and through resistance R to conductor 33 and thence to line L as last traced. Subsequent reclosure of switch 22 completes the circuit through the motor, field and winding of relay 25 as previously traced, thence by conductors 32, 36 and 37 through switch 22 and the winding of relay 26 thence by conductors 38 and 39 through switch 2% and by conductor 35 to line L.

The control circuits, which serve to effect the aforedescribed operation of the electro responsive switches automatically, may be traced as follows: Closure of the starting button 29 completes the energizing circuit of switch 21, said circuit extending from line L by conductor 40 through said starting button, thence by conductor 11 through the down contacts a of switch 23, thence by conductor 42 through relay 28, the winding of which, however, does not become energized until closure of switch 23, thence by conductor 43 through the winding of switch 21 and by conductor d4 through stop switch 30 to line L. Switch 21, upon closure, maintains itself by circuit connections extending from line L by conductor 40 through auxili ary contacts d of said switch, thence by conductors s5 and 41 through the down contacts a, of switch 23, thence through the winding of said switch 21, to line L as last traced.

Closure of switch 21 also completes the energizing circuit of switch 22, said circuit extending from conductor i0 through auxiliary contacts e of switch 21, by conductor 46 through relay 25, by conductor i7 through the winding of switch 22 and by conductors 18 and as through the stop button to line L.- Switch 22 thereupon closes subject to delay by the action of relay 25 and upon closing completes a maintaining circuit for itself subject to interruption upon opening of switch 21 said circuit extending through auxiliary contacts a of switch 21, as last traced, thence by conductors 46 and a9 through auxiliary contacts f of switch 22, by conductor 50 through the winding of switch 22 and to line L as last traced.

Closure of switch 22 furthermore completes the energizing circuit of switch 23, said circuit extending from conductor 40 through auxiliary contacts 9 of switch 22, by conductor 51 through relay 26 thence by conductor 52 through the winding of switch 23 and by conductors 53 and 14 through the stop button to line L. Switch 23 thereupon closes subject to delay by relay 26 and upon closure completes a maintaining circuit for itself extending from conductor 40 through auxiliary contacts Z) of switch 23, thence by conductors 54: and 52 through the winding of said switch to line L as last traced.

Closure of switch 23 also serves through 1 ,neavea opening of its down contacts a "to interrupt Eire maintaining circuit of swatch 21 which thereupon opens and also interrupts 'the circuit ofswitdh "22 which likewise opens.

Closure of switch 23 furthermore completes the energizing of switch 24, said circuit extending by conductor 40 through auxiliary contacts of switch 23, thence by conductor 55 through relay 27, by conductor 56 through the winding of switch 24 thence by conductors 57 and to line L. Switch 24 thereupon closes subject to delay by relay 27 and upon closure i maintains itself by circuit connections which depend upon closure of switch 23 and extend to auxiliary contacts 0 of switch 23 as last traced, thence by conductors and 58 to auxiliary contacts 72 of switch 24, thence by conductor 56 through the winding of switch 24 to line L as last traced.

Closure of switch 24 also completes an en ergizing circuit for switch 21 for causing reclosure thereof, said circuit extending by conductor 40 to and through auxiliary contacts i of switch 24, thence by conductor 59 around but not through auxiliary contacts a of switch 23 which are now open, thence through the winding of switch 21 as formerly traced. Switch 1 is thereupon adapted to close subject, however, to delay by relay 28, and to remain closed so long as switch 24 remains closed, closure of the latter switch being also, as aforestated, dependent upon closure of switch 23. Closure of switch 21 also serves to cause reclosure and maintainance of switch 22 inthe manner already described, thereby completing the cycle of operation of the controller for starting and accele ation of the motor.

Opening of the stop button 30 at any stage of the foregoing operation causes de-energization of any switch or switches then closed, thereby arresting automatic action of the controller if in progress, stoppin the motor and insuring against restarting t ereof except in the manner aforedescribed.

From the foregoing it is obvious that closure of each switch except the first is subject to control through a series relay whereas the maintaining circuits of said switches are independent of said relays. The windings of said relays are moreover so arranged as to be traversed by the full motor current prior to and until closure of the switches respectively controlled thereby, such arrangement assuring positive and uniform action of said relays for delaying closure of their respective switches until in each instance the current has subsided to a safe value.

While the aforedescribed controllers each include but three resistance sections and four control switches therefor, it is believed to be obvious to any one skilled in the controller art that the same idea may be advair tageously applied to controllers embodying numbers sections and "switches either gzreafter or less than those stated.

What I claim as new and desire to secure by Letters Patent is E1. 111 a \circuit controller for an electric motor, the combination with a plurality of resistance sections, of separately operable single-pole control switches therefor, one of said switches adapted upon closure thereof to effect inclusion of all of said resistance sections in circuit in series with one another, another of said switches adapted upon closure thereof to effect exclusion of one of said resistance sections, a third switch adapted upon closure thereof to effect exclusion of another of said resistance sections, and a fourth switch adapted upon closure thereof to effect parallel connection of two of said resistance sections, means for insuring opening of said first-mentioned and second-mentioned switches prior to closure of said fourth ,switch, means for thereafter effecting reclosure of said first-mentioned switch to provide for inclusion of all of said resistance sections in parallel with each other, and means for thereafter effecting reclosure of said second-mentioned switch to provide for short-circuiting of all of said resistance sections through the contacts of said switch and the fourth switch.

2. In a circuit controller for an electric motor, the combination with three resistance sections, of four separately operable singlepole control switches therefor, the first switch adapted upon closure thereof to effect inclusion of all of said resistance sections in circuit in series with one another, the second switch adapted upon closure thereof to effect exclusion of one of said resistance sections, the third switch adapted upon closure thereof to effect exclusion of another of said resistance sections, said first and second switches being opened and the fourth switch thereafter closed to effect parallel circuit connections for two of said resistance sections, the first switch adapted upon reclosure thereof to effect parallel circuit connections for all of said resistance sections, the second switch adapted upon reclosure thereof to effect short-circuiting of all of said resistance sections, and means for insuring operation of said switches in the sequence aforedescribed.

3. In a circuit controller for an electric motor, the combination with three resistance sections adapted to be connected in the mo tor circuit, of four separately operable single-pole control switches for said circuit, means providing for operation of said switches automatically and in a definite sequence to complete said circuit through all of said sections in series, thereafter to exelude all but one of said sections sequentially and subsequently reinclude the same sequentially in parallel with said section and with one another two of said switches being adapted upon simultaneous closure thereof to effect short-circuiting of all of said resistance sections and means subjecting the action of said switches to regulation in accordance with the electrical conditions of said circuit.

In witness whereof, I have hereunto subscribed iny name.

CHARLES W. YERGER. 

